quota: clean up checks for supported quota methods
[linux-2.6.git] / fs / quota / quota.c
1 /*
2  * Quota code necessary even when VFS quota support is not compiled
3  * into the kernel.  The interesting stuff is over in dquot.c, here
4  * we have symbols for initial quotactl(2) handling, the sysctl(2)
5  * variables, etc - things needed even when quota support disabled.
6  */
7
8 #include <linux/fs.h>
9 #include <linux/namei.h>
10 #include <linux/slab.h>
11 #include <asm/current.h>
12 #include <asm/uaccess.h>
13 #include <linux/compat.h>
14 #include <linux/kernel.h>
15 #include <linux/security.h>
16 #include <linux/syscalls.h>
17 #include <linux/buffer_head.h>
18 #include <linux/capability.h>
19 #include <linux/quotaops.h>
20 #include <linux/types.h>
21 #include <net/netlink.h>
22 #include <net/genetlink.h>
23
24 /* Check validity of generic quotactl commands */
25 static int generic_quotactl_valid(struct super_block *sb, int type, int cmd,
26                                   qid_t id)
27 {
28         if (type >= MAXQUOTAS)
29                 return -EINVAL;
30         if (!sb && cmd != Q_SYNC)
31                 return -ENODEV;
32         /* Is operation supported? */
33         if (sb && !sb->s_qcop)
34                 return -ENOSYS;
35
36         /* Check privileges */
37         if (cmd == Q_GETQUOTA) {
38                 if (((type == USRQUOTA && current_euid() != id) ||
39                      (type == GRPQUOTA && !in_egroup_p(id))) &&
40                     !capable(CAP_SYS_ADMIN))
41                         return -EPERM;
42         }
43         else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
44                 if (!capable(CAP_SYS_ADMIN))
45                         return -EPERM;
46
47         return 0;
48 }
49
50 /* Check validity of XFS Quota Manager commands */
51 static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd,
52                               qid_t id)
53 {
54         if (type >= XQM_MAXQUOTAS)
55                 return -EINVAL;
56         if (!sb)
57                 return -ENODEV;
58         if (!sb->s_qcop)
59                 return -ENOSYS;
60
61         /* Check privileges */
62         if (cmd == Q_XGETQUOTA) {
63                 if (((type == XQM_USRQUOTA && current_euid() != id) ||
64                      (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
65                      !capable(CAP_SYS_ADMIN))
66                         return -EPERM;
67         } else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
68                 if (!capable(CAP_SYS_ADMIN))
69                         return -EPERM;
70         }
71
72         return 0;
73 }
74
75 static int check_quotactl_valid(struct super_block *sb, int type, int cmd,
76                                 qid_t id)
77 {
78         int error;
79
80         if (XQM_COMMAND(cmd))
81                 error = xqm_quotactl_valid(sb, type, cmd, id);
82         else
83                 error = generic_quotactl_valid(sb, type, cmd, id);
84         if (!error)
85                 error = security_quotactl(cmd, type, id, sb);
86         return error;
87 }
88
89 #ifdef CONFIG_QUOTA
90 void sync_quota_sb(struct super_block *sb, int type)
91 {
92         int cnt;
93
94         if (!sb->s_qcop->quota_sync)
95                 return;
96
97         sb->s_qcop->quota_sync(sb, type);
98
99         if (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE)
100                 return;
101         /* This is not very clever (and fast) but currently I don't know about
102          * any other simple way of getting quota data to disk and we must get
103          * them there for userspace to be visible... */
104         if (sb->s_op->sync_fs)
105                 sb->s_op->sync_fs(sb, 1);
106         sync_blockdev(sb->s_bdev);
107
108         /*
109          * Now when everything is written we can discard the pagecache so
110          * that userspace sees the changes.
111          */
112         mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
113         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
114                 if (type != -1 && cnt != type)
115                         continue;
116                 if (!sb_has_quota_active(sb, cnt))
117                         continue;
118                 mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex,
119                                   I_MUTEX_QUOTA);
120                 truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
121                 mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
122         }
123         mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
124 }
125 #endif
126
127 static void sync_dquots(int type)
128 {
129         struct super_block *sb;
130         int cnt;
131
132         spin_lock(&sb_lock);
133 restart:
134         list_for_each_entry(sb, &super_blocks, s_list) {
135                 /* This test just improves performance so it needn't be
136                  * reliable... */
137                 for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
138                         if (type != -1 && type != cnt)
139                                 continue;
140                         if (!sb_has_quota_active(sb, cnt))
141                                 continue;
142                         if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
143                            list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
144                                 continue;
145                         break;
146                 }
147                 if (cnt == MAXQUOTAS)
148                         continue;
149                 sb->s_count++;
150                 spin_unlock(&sb_lock);
151                 down_read(&sb->s_umount);
152                 if (sb->s_root)
153                         sync_quota_sb(sb, type);
154                 up_read(&sb->s_umount);
155                 spin_lock(&sb_lock);
156                 if (__put_super_and_need_restart(sb))
157                         goto restart;
158         }
159         spin_unlock(&sb_lock);
160 }
161
162 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
163                          void __user *addr)
164 {
165         char *pathname;
166         int ret = -ENOSYS;
167
168         pathname = getname(addr);
169         if (IS_ERR(pathname))
170                 return PTR_ERR(pathname);
171         if (sb->s_qcop->quota_on)
172                 ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
173         putname(pathname);
174         return ret;
175 }
176
177 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
178 {
179         __u32 fmt;
180
181         down_read(&sb_dqopt(sb)->dqptr_sem);
182         if (!sb_has_quota_active(sb, type)) {
183                 up_read(&sb_dqopt(sb)->dqptr_sem);
184                 return -ESRCH;
185         }
186         fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
187         up_read(&sb_dqopt(sb)->dqptr_sem);
188         if (copy_to_user(addr, &fmt, sizeof(fmt)))
189                 return -EFAULT;
190         return 0;
191 }
192
193 static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
194 {
195         struct if_dqinfo info;
196         int ret;
197
198         if (!sb_has_quota_active(sb, type))
199                 return -ESRCH;
200         if (!sb->s_qcop->get_info)
201                 return -ENOSYS;
202         ret = sb->s_qcop->get_info(sb, type, &info);
203         if (!ret && copy_to_user(addr, &info, sizeof(info)))
204                 return -EFAULT;
205         return ret;
206 }
207
208 static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
209 {
210         struct if_dqinfo info;
211
212         if (copy_from_user(&info, addr, sizeof(info)))
213                 return -EFAULT;
214         if (!sb_has_quota_active(sb, type))
215                 return -ESRCH;
216         if (!sb->s_qcop->set_info)
217                 return -ENOSYS;
218         return sb->s_qcop->set_info(sb, type, &info);
219 }
220
221 static int quota_getquota(struct super_block *sb, int type, qid_t id,
222                           void __user *addr)
223 {
224         struct if_dqblk idq;
225         int ret;
226
227         if (!sb_has_quota_active(sb, type))
228                 return -ESRCH;
229         if (!sb->s_qcop->get_dqblk)
230                 return -ENOSYS;
231         ret = sb->s_qcop->get_dqblk(sb, type, id, &idq);
232         if (ret)
233                 return ret;
234         if (copy_to_user(addr, &idq, sizeof(idq)))
235                 return -EFAULT;
236         return 0;
237 }
238
239 static int quota_setquota(struct super_block *sb, int type, qid_t id,
240                           void __user *addr)
241 {
242         struct if_dqblk idq;
243
244         if (copy_from_user(&idq, addr, sizeof(idq)))
245                 return -EFAULT;
246         if (!sb_has_quota_active(sb, type))
247                 return -ESRCH;
248         if (!sb->s_qcop->set_dqblk)
249                 return -ENOSYS;
250         return sb->s_qcop->set_dqblk(sb, type, id, &idq);
251 }
252
253 static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
254 {
255         __u32 flags;
256
257         if (copy_from_user(&flags, addr, sizeof(flags)))
258                 return -EFAULT;
259         if (!sb->s_qcop->set_xstate)
260                 return -ENOSYS;
261         return sb->s_qcop->set_xstate(sb, flags, cmd);
262 }
263
264 static int quota_getxstate(struct super_block *sb, void __user *addr)
265 {
266         struct fs_quota_stat fqs;
267         int ret;
268
269         if (!sb->s_qcop->get_xstate)
270                 return -ENOSYS;
271         ret = sb->s_qcop->get_xstate(sb, &fqs);
272         if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
273                 return -EFAULT;
274         return ret;
275 }
276
277 static int quota_setxquota(struct super_block *sb, int type, qid_t id,
278                            void __user *addr)
279 {
280         struct fs_disk_quota fdq;
281
282         if (copy_from_user(&fdq, addr, sizeof(fdq)))
283                 return -EFAULT;
284         if (!sb->s_qcop->set_xquota)
285                 return -ENOSYS;
286         return sb->s_qcop->set_xquota(sb, type, id, &fdq);
287 }
288
289 static int quota_getxquota(struct super_block *sb, int type, qid_t id,
290                            void __user *addr)
291 {
292         struct fs_disk_quota fdq;
293         int ret;
294
295         if (!sb->s_qcop->get_xquota)
296                 return -ENOSYS;
297         ret = sb->s_qcop->get_xquota(sb, type, id, &fdq);
298         if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
299                 return -EFAULT;
300         return ret;
301 }
302
303 /* Copy parameters and call proper function */
304 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
305                        void __user *addr)
306 {
307         switch (cmd) {
308         case Q_QUOTAON:
309                 return quota_quotaon(sb, type, cmd, id, addr);
310         case Q_QUOTAOFF:
311                 if (!sb->s_qcop->quota_off)
312                         return -ENOSYS;
313                 return sb->s_qcop->quota_off(sb, type, 0);
314         case Q_GETFMT:
315                 return quota_getfmt(sb, type, addr);
316         case Q_GETINFO:
317                 return quota_getinfo(sb, type, addr);
318         case Q_SETINFO:
319                 return quota_setinfo(sb, type, addr);
320         case Q_GETQUOTA:
321                 return quota_getquota(sb, type, id, addr);
322         case Q_SETQUOTA:
323                 return quota_setquota(sb, type, id, addr);
324         case Q_SYNC:
325                 if (sb) {
326                         if (!sb->s_qcop->quota_sync)
327                                 return -ENOSYS;
328                         sync_quota_sb(sb, type);
329                 } else
330                         sync_dquots(type);
331                 return 0;
332         case Q_XQUOTAON:
333         case Q_XQUOTAOFF:
334         case Q_XQUOTARM:
335                 return quota_setxstate(sb, cmd, addr);
336         case Q_XGETQSTAT:
337                 return quota_getxstate(sb, addr);
338         case Q_XSETQLIM:
339                 return quota_setxquota(sb, type, id, addr);
340         case Q_XGETQUOTA:
341                 return quota_getxquota(sb, type, id, addr);
342         case Q_XQUOTASYNC:
343                 if (!sb->s_qcop->quota_sync)
344                         return -ENOSYS;
345                 return sb->s_qcop->quota_sync(sb, type);
346         default:
347                 return -EINVAL;
348         }
349 }
350
351 /*
352  * look up a superblock on which quota ops will be performed
353  * - use the name of a block device to find the superblock thereon
354  */
355 static struct super_block *quotactl_block(const char __user *special)
356 {
357 #ifdef CONFIG_BLOCK
358         struct block_device *bdev;
359         struct super_block *sb;
360         char *tmp = getname(special);
361
362         if (IS_ERR(tmp))
363                 return ERR_CAST(tmp);
364         bdev = lookup_bdev(tmp);
365         putname(tmp);
366         if (IS_ERR(bdev))
367                 return ERR_CAST(bdev);
368         sb = get_super(bdev);
369         bdput(bdev);
370         if (!sb)
371                 return ERR_PTR(-ENODEV);
372
373         return sb;
374 #else
375         return ERR_PTR(-ENODEV);
376 #endif
377 }
378
379 /*
380  * This is the system call interface. This communicates with
381  * the user-level programs. Currently this only supports diskquota
382  * calls. Maybe we need to add the process quotas etc. in the future,
383  * but we probably should use rlimits for that.
384  */
385 SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
386                 qid_t, id, void __user *, addr)
387 {
388         uint cmds, type;
389         struct super_block *sb = NULL;
390         int ret;
391
392         cmds = cmd >> SUBCMDSHIFT;
393         type = cmd & SUBCMDMASK;
394
395         if (cmds != Q_SYNC || special) {
396                 sb = quotactl_block(special);
397                 if (IS_ERR(sb))
398                         return PTR_ERR(sb);
399         }
400
401         ret = check_quotactl_valid(sb, type, cmds, id);
402         if (ret >= 0)
403                 ret = do_quotactl(sb, type, cmds, id, addr);
404         if (sb)
405                 drop_super(sb);
406
407         return ret;
408 }
409
410 #if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
411 /*
412  * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
413  * and is necessary due to alignment problems.
414  */
415 struct compat_if_dqblk {
416         compat_u64 dqb_bhardlimit;
417         compat_u64 dqb_bsoftlimit;
418         compat_u64 dqb_curspace;
419         compat_u64 dqb_ihardlimit;
420         compat_u64 dqb_isoftlimit;
421         compat_u64 dqb_curinodes;
422         compat_u64 dqb_btime;
423         compat_u64 dqb_itime;
424         compat_uint_t dqb_valid;
425 };
426
427 /* XFS structures */
428 struct compat_fs_qfilestat {
429         compat_u64 dqb_bhardlimit;
430         compat_u64 qfs_nblks;
431         compat_uint_t qfs_nextents;
432 };
433
434 struct compat_fs_quota_stat {
435         __s8            qs_version;
436         __u16           qs_flags;
437         __s8            qs_pad;
438         struct compat_fs_qfilestat      qs_uquota;
439         struct compat_fs_qfilestat      qs_gquota;
440         compat_uint_t   qs_incoredqs;
441         compat_int_t    qs_btimelimit;
442         compat_int_t    qs_itimelimit;
443         compat_int_t    qs_rtbtimelimit;
444         __u16           qs_bwarnlimit;
445         __u16           qs_iwarnlimit;
446 };
447
448 asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
449                                                 qid_t id, void __user *addr)
450 {
451         unsigned int cmds;
452         struct if_dqblk __user *dqblk;
453         struct compat_if_dqblk __user *compat_dqblk;
454         struct fs_quota_stat __user *fsqstat;
455         struct compat_fs_quota_stat __user *compat_fsqstat;
456         compat_uint_t data;
457         u16 xdata;
458         long ret;
459
460         cmds = cmd >> SUBCMDSHIFT;
461
462         switch (cmds) {
463         case Q_GETQUOTA:
464                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
465                 compat_dqblk = addr;
466                 ret = sys_quotactl(cmd, special, id, dqblk);
467                 if (ret)
468                         break;
469                 if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
470                         get_user(data, &dqblk->dqb_valid) ||
471                         put_user(data, &compat_dqblk->dqb_valid))
472                         ret = -EFAULT;
473                 break;
474         case Q_SETQUOTA:
475                 dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
476                 compat_dqblk = addr;
477                 ret = -EFAULT;
478                 if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
479                         get_user(data, &compat_dqblk->dqb_valid) ||
480                         put_user(data, &dqblk->dqb_valid))
481                         break;
482                 ret = sys_quotactl(cmd, special, id, dqblk);
483                 break;
484         case Q_XGETQSTAT:
485                 fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
486                 compat_fsqstat = addr;
487                 ret = sys_quotactl(cmd, special, id, fsqstat);
488                 if (ret)
489                         break;
490                 ret = -EFAULT;
491                 /* Copying qs_version, qs_flags, qs_pad */
492                 if (copy_in_user(compat_fsqstat, fsqstat,
493                         offsetof(struct compat_fs_quota_stat, qs_uquota)))
494                         break;
495                 /* Copying qs_uquota */
496                 if (copy_in_user(&compat_fsqstat->qs_uquota,
497                         &fsqstat->qs_uquota,
498                         sizeof(compat_fsqstat->qs_uquota)) ||
499                         get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
500                         put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
501                         break;
502                 /* Copying qs_gquota */
503                 if (copy_in_user(&compat_fsqstat->qs_gquota,
504                         &fsqstat->qs_gquota,
505                         sizeof(compat_fsqstat->qs_gquota)) ||
506                         get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
507                         put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
508                         break;
509                 /* Copying the rest */
510                 if (copy_in_user(&compat_fsqstat->qs_incoredqs,
511                         &fsqstat->qs_incoredqs,
512                         sizeof(struct compat_fs_quota_stat) -
513                         offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
514                         get_user(xdata, &fsqstat->qs_iwarnlimit) ||
515                         put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
516                         break;
517                 ret = 0;
518                 break;
519         default:
520                 ret = sys_quotactl(cmd, special, id, addr);
521         }
522         return ret;
523 }
524 #endif
525
526
527 #ifdef CONFIG_QUOTA_NETLINK_INTERFACE
528
529 /* Netlink family structure for quota */
530 static struct genl_family quota_genl_family = {
531         .id = GENL_ID_GENERATE,
532         .hdrsize = 0,
533         .name = "VFS_DQUOT",
534         .version = 1,
535         .maxattr = QUOTA_NL_A_MAX,
536 };
537
538 /**
539  * quota_send_warning - Send warning to userspace about exceeded quota
540  * @type: The quota type: USRQQUOTA, GRPQUOTA,...
541  * @id: The user or group id of the quota that was exceeded
542  * @dev: The device on which the fs is mounted (sb->s_dev)
543  * @warntype: The type of the warning: QUOTA_NL_...
544  *
545  * This can be used by filesystems (including those which don't use
546  * dquot) to send a message to userspace relating to quota limits.
547  *
548  */
549
550 void quota_send_warning(short type, unsigned int id, dev_t dev,
551                         const char warntype)
552 {
553         static atomic_t seq;
554         struct sk_buff *skb;
555         void *msg_head;
556         int ret;
557         int msg_size = 4 * nla_total_size(sizeof(u32)) +
558                        2 * nla_total_size(sizeof(u64));
559
560         /* We have to allocate using GFP_NOFS as we are called from a
561          * filesystem performing write and thus further recursion into
562          * the fs to free some data could cause deadlocks. */
563         skb = genlmsg_new(msg_size, GFP_NOFS);
564         if (!skb) {
565                 printk(KERN_ERR
566                   "VFS: Not enough memory to send quota warning.\n");
567                 return;
568         }
569         msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
570                         &quota_genl_family, 0, QUOTA_NL_C_WARNING);
571         if (!msg_head) {
572                 printk(KERN_ERR
573                   "VFS: Cannot store netlink header in quota warning.\n");
574                 goto err_out;
575         }
576         ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type);
577         if (ret)
578                 goto attr_err_out;
579         ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id);
580         if (ret)
581                 goto attr_err_out;
582         ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
583         if (ret)
584                 goto attr_err_out;
585         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
586         if (ret)
587                 goto attr_err_out;
588         ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
589         if (ret)
590                 goto attr_err_out;
591         ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
592         if (ret)
593                 goto attr_err_out;
594         genlmsg_end(skb, msg_head);
595
596         genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
597         return;
598 attr_err_out:
599         printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
600 err_out:
601         kfree_skb(skb);
602 }
603 EXPORT_SYMBOL(quota_send_warning);
604
605 static int __init quota_init(void)
606 {
607         if (genl_register_family(&quota_genl_family) != 0)
608                 printk(KERN_ERR
609                        "VFS: Failed to create quota netlink interface.\n");
610         return 0;
611 };
612
613 module_init(quota_init);
614 #endif
615